This invention relates to advanced neutron absorbing materials and more specifically to neutron absorbing materials utilizing rare earth elements such as gadolinium, europium and samarium in amorphous metallic glasses and/or noble based nano/microcrystalline materials.
The need for better neutron absorbing materials has become an issue in the disposition of highly enriched spent nuclear fuels (SNF). Boron based neutron absorbing alloys have limited neutron capturing capabilities which can decrease with the loss of boron though leaching. Cost effectiveness prompts an optimum loading of the enriched SNF in canisters. Loading efficiencies of the canisters can be improved by including neutron absorbing materials as structural components or as backfill to ensure that subcritical conditions are maintained.
Nearly all present day nuclear absorber materials are designed with careful and detailed consideration to the nuclear, mechanical, and corrosion characteristics of the alloys. Additional factors such as fabrication ability and the cost and availability of the starting materials are also important considerations in selecting neutron absorber materials.
Rare earth elements (lanthanum through lutetium), and more specifically gadolinium, samarium and europium are good candidate elements for neutron absorber materials due to their extremely high microscopic neutron capture cross sections. However, rare earth elements in their pure form cannot be directly used for these absorber applications because the corrosion resistance of these elements is exceedingly poor.
It is an object of the present invention to provide a noble metallic matrix incorporating rare earth elements whereby the rare earth elements are protected from corrosion, oxidation and leach resistance.
It is another object of the present invention to provide an amorphous metallic glass and/or nano/microcrystalline material (hereinafter sometimes referred to as fine crystalline structure) designed with corrosion resistance and having high macroscopic nuclear cross sections.
It is still a further purpose of the present invention to provide a material in particulate form that can also be processed into consolidated forms making it useful for many nuclear applications where criticality control is desired.